Examining ankle joint laxity using two different knee positions and with simulated muscle guarding

Hanlon, Shawn
Journal Title
Journal ISSN
Volume Title
University of Delaware
Context: Anterior drawer and talar tilt tests are commonly used to manually assess lateral ankle sprains. Several factors affect the reliability of these tests including the individual clinician's experience and skill, knee positioning, and muscle guarding. Objectives: To compare involuntary activity of the gastrocnemius during laxity testing at different knee positions. Secondarily to compare these laxity measurements during a simulated situation of muscle guarding. Design: A repeated-measures design with knee position as the independent variable. Setting: University research laboratory. Participants: 33 healthy volunteer subjects (16 male, 17 female) between ages 18-25 were tested. Interventions: The ankle was loaded under 2 test conditions (relaxed, simulated muscle guarding) at two knee positions (0°, 90° flexion) while recording gastrocnemius EMG activity. Main Outcome Measures: Anterior displacement (mm), IE motion (degrees of motion), peak EMG values of the gastrocnemius (mV). Results: Anterior displacement was significantly different at 90° knee flexion compared to 0° (P = .007). IE motion was significantly greater at 0° knee flexion compared to 90° knee flexion (P < .001). Peak EMG activity of the gastrocnemius was significantly different at 90° knee flexion during anterior displacement (P < .001). Simulated muscle guarding significantly reduced anterior displacement compared to the relaxed condition (90° knee flexion, P = .016; 0° knee flexion, P = .008) and reduced IE motion (90° knee flexion P < .001; 0° knee flexion, P = .03). Conclusions: Involuntary muscle activity of the gastrocnemius does not appear to affect ankle laxity at different knee positioning. Additionally, knee position did not affect laxity measurements during simulated anterior drawer testing. However Talar tilt testing may be best performed with the knee in the 0° knee flexion position. Lastly, simulated muscle guarding significantly reduced ankle laxity and should be a consideration when performing theses clinical examination techniques. Key words: ankle arthrometer, anterior drawer, talar tilt, electromyography, manual examination.